Florida 'lab' tests best ways to build to use the sun

Can one 1,300-square-foot building change the building industry in the Southeast? Officials at the Florida Solar Energy Center (FSEC) are cautiously optimistic that it can.

The building is the FSEC's new passive cooling laboratory with interchangeable walls.

Passive cooling is a discipline whereby the building structure itself provides a substantial amount of the cooling, explains the building's designer and FSEC passive analyst Philip Fairey. Consesquently, it was no small challenge to design a lab which would test the energy efficiency of various wall, ceiling, and ventilation designs.

Rather than build dozens of structures, Mr. Fairey designed what he calls a reconfigurable laboratory; in other words, a laboratory that tests itself.

Passive solar energy is not a new concept. The ancient Persians, for example, built wind towers which would catch drafts above the ground and channel them underground and into the relatively cool basement areas, thus creating indoor air motion in desert conditions.

Ancestors of the Pueblo Indians in the American Southwest built cliff dwellings, such as those at Mesa Verde National Park, which were roofless to allow exhaust and create air flow.

There are many examples of passive cooling, some of which are still in use, around the world. But under today's complex economic structure, passive cooling is something of a lost art. And the sad fact is that it was lost before it was ever fully developed and exploited.

Researchers at the passive-energy lab here hope to change all that.

In the main, passive cooling is based on simple scientific principles, such as:

* Hot air rises and can be exhausted to cause air circulation.

* The sun is higher in the sky in the summer and thus overhangs can be designed to block the summer sun and yet allow the warmth of the winter sun to penetrate.

* Deciduous trees lose their leaves in the winter and so a properly landscped house can be shaded in the summer and enjoy the sun in the winter.

Why don't all modern houses use these basic but effective techniques?

Many of us are living in houses that were designed in the age of cheap energy. And the majority of homes now under construction are, from an energy standpoint, throwbacks on those earlier designers.

It's easy enough for a builder to add extra insulation or a couple of familiar passive elements right now, but to really build a passive home you are looking at a matrix of variables starting with the buyer's demands and involving the architects, builders, and bankers.

The point is, it is far easier and, on a superficial level, cheaper to build traditional housing.

Most bankers don't want to hold a 30-year mortgage on an unproven home style. Moreoever, an air conditioner has specific Btu and energy-efficiency ratings. For most passive-cooling elements there is no common denominator or anything to go back on.

''There is a drastic need for this data,'' exhorts Mr. Fairey.

''Savings and loan institutions,'' he explains, ''are not going to lend money on experimental houses. So if we do the experimenting here and provide people with good hard data, then the people who lend the money and the people who build the houses will be much less reluctant to incorporate these techniques into new buildings.

''The energy experts at Florida's solar center admit that passive cooling is not likely to supplant air conditioning. Their goal is to prove that passive techniques belong in the mainstream of the building industry. Ultimately, if the techniques are plugged into the industry, Mr. Fairey says he feels it would be reasonable to expect houses of the future to use 50 percent less energy.

''In certain cases you can save up to that much just by properly orienting the building,'' he explains.

Surprisingly, the cost to add passive features on a house is generally between zero and 5 percent of the building cost. The proponents of passive solar energy feel that fact alone should be attractive to the buyer because it is a good return on his investment. Also, it could be attractive to the builder from a marketing standpoint.

The key to getting that good return on investment, however, is more than just discerning what works. It is proving what works efficiently and affordably and can be accomplished with standard building materials.

Fairey says such research has been done for passive solar heating, but little has been done on passive cooling. However, he adds that there are other passive laboratories, but they focus on specific applications, such as solar roof ponds, a technique that allows for passive heating and cooling.''

Aside from that, the only other passive cooling labs I know of are concerned with reconfigurable internal walls,'' he says. ''We felt the problem was the exterior walls. As far as I know this is the only such passive laboratory in the nation.''

The laboratory is a roof supported by steel columns. The experimental walls can be changed for each experiment because they do not provide support.

If Fairey wants to test a particular wall on the sun-oriented south side only , he can attach environmental barriers to the steel columns on the other three sides. A large-capacity computer hooked into the solar center's meteorological center records even minuscule changes in the performance of the walls relative to the weather.

The lab will be used initially to focus on three topics:

* How to prevent heat gain by using radiant barriers, vegetation, shading, and other techniques.

* How to reject heat through dehumidification, natural ventilation, and other methods.

* The thermal effects of mass or building materials. For example, does a particular wood wall conduct more heat than a particular block wall?

Fairey also says his research team is interested in the specific advantages of interior designs, such as standard ceilings vs. cathedral ceilings. They will study underfloor ventilation and attic insulation as well.

''Florida is an excellent testing ground for passive cooling because of the extreme conditions,'' asserts Jerry Ventre, deputy director of the FSEC. ''This (central Florida) is about the harshest area as far as comfort level goes,'' he adds. ''The only area that is worse is the Everglades.''

Mr. Ventre says he feels the passive systems which work best in this hot, humid, high-tech capital will easily prove their worth just about anywhere else.